The present technology relates to illumination of illumination targets, and more specifically, to assemblies for illuminating illumination targets for imaging systems.
In imaging and other systems, it can be useful to illuminate a target with a high quality illumination pattern. For example, machine vision systems can be configured to capture images of an object or process, analyze the images to identify relevant characteristics, actions, and so on, and instruct various devices (e.g., manufacturing or sorting devices) based upon the image analysis. In this context, the quality of the illumination pattern used can directly affect the quality of the images captured and thereby affect the utility and accuracy of the resulting image analysis. Accordingly, there is a need for high quality illumination assemblies for machine vision and other systems.
Conventional illumination assemblies can include bare illumination assemblies, in which illumination is provided from light sources to illumination targets without intervening diffusers or other secondary optics. Bare illumination can create generally circular illumination patterns with Gaussian (or Gaussian-like) intensity profiles, such that central areas of the illumination patterns are significantly brighter than the edges. This can result in low light efficiency, as a significant portion of light from the light sources can fall outside the relevant areas (e.g., fields of view of associated imaging devices). Similarly, given the non-uniformity of the intensity profiles, relatively powerful light sources or a relatively large number of overlapping light sources may be needed to cover the relevant area (e.g., the fields of view of the imaging devices) with sufficiently intense illumination.
Conventional illumination assemblies can also include light sources in combination with secondary optics such as aspherical or free-form lenses. However, conventional secondary optics systems can be difficult and expensive to implement. Further, use of conventional secondary optics can also result in low lighting efficiency, and may not produce suitable illumination patterns for some applications.